Rex Owen  

, レックス・オーエン

Max has a friend named Rex who was discovered as an infant by paleontologist Dr. Owen in an egg-like container within a dinosaur exhibit in New York City. Now 12 years old, Rex lives with Max and his family while his father searches for fossils. Dr. Owen is also a close friend of the family. Rex's partner is a Carnotaurus named Ace. Despite being a kind-hearted boy, Rex has always been short-tempered. In addition to this, he enjoys playing the violin.